Arrangement and method for electrically controlling the intensity of unpolarized light

ABSTRACT

In an arrangement and a method for electrically controlling the intensity of non-polarized light, a polarizing beam splitter is acted upon by the light to be controlled via an input face such that the light is split into two polarized light bundles that are orthogonal with respect to each other. Provision is made that a first reflecting device is configured for the reflection of at least one of the polarized light bundles, so that both polarized light bundles run in parallel. At least one electro-optical element is provided in a path of the parallel running polarized light bundles. The polarization is changed as a function of the supplied control voltage. Also provided is a second reflecting device for reflecting the light bundles in the opposite direction. The light bundles pass through the at least one electro-optical element twice and are directed by the first reflecting device to the polarizing beam splitter, and the controlled light can be extracted from at least one output face of the polarizing beam splitter.

BACKGROUND INFORMATION

The present invention concerns an arrangement and a method for theelectrical control of the intensity of non-polarized light, a polarizingbeam splitter being acted upon by the light to be controlled via aninput face such that the light is split into two polarized light bundlesthat are orthogonal with respect to each other.

For a multiplicity of applications in the area of optics, for example ininformation-processing, in laser technology, and for many geodetic,astronomical, and navigational applications, arrangements are requiredwhich can switch light, carry out switchovers between optical channels,or modulate.

In known electro-optical switches and modulators of this type, eitheroptically effective solid-body crystals or liquid crystals are used.Transparent crystals, such as can be manufactured from LiNbO3, requirehigh working voltages, permit only small apertures, and are costintensive. On account of the small permissible light bundle diameters,they are little suited for switching light bundles that contain images.As a consequence of the high dispersion that is inherent in them, theuse of monochromatic light sources (lasers) is also necessary. Theoptical and electrical parameters change during use and thus impair theproperties of the electro-optical switch or modulator. In addition, halfof the light is lost, since these switches and modulators are employedin connection with polarizers.

In optical modulators that are improved with respect to theseproperties, modulators that have become known through German PublishedPatent Application No. 30 13 498 and British Patent No. 2046937 bothpolarization directions are used in connection with a polarizing beamsplitter. However, the other cited disadvantages remain. Furthermore, itis disadvantageous in the known modulator that they require a workingvoltage of over 100 volts. In addition, significant costs arise as aresult of a necessary cascading of the modulator.

In a further known arrangement, which was described by Hirabayashi, T.Kurokawa in “Liquid Crystal Devices for Optical Communication andInformation-processing Systems,” Liquid Crystals, Volume 14, pp. 307-317(1993), a nematic liquid crystal is used in a so-called twistarrangement. In this context, larger apertures can be achieved. However,in nematic liquid crystals, their great switching times of, for example,several 100 milliseconds and problems in the representation ofintermediate values are disadvantageous. Through Chiung-Shevy Wu, ShineTsou Wu: “New Liquid Crystal Operation Modes,” Volume 2949 SPIE, ImageSciences and Display Technologies, Proceedings Berlin Conference, FRG,7-10 (1996), a modulator has become known in which the two polarizationstates s and p, generated by a polarizing beam splitter, are conveyed inthe reverse direction by electro-optical liquid crystal cell. This leadsto high rotation angles. However, the cells having a switching frequencyof roughly 10 Hz are too slow.

From German Published Patent Application No. 196 31 644 (correspondingto PCT Publication No. WO 98/06002), an arrangement is known forswitching optical patterns, which has a high switching efficiency andusing which non-polarized, polychromatic light can be switchedsufficiently rapidly. The arrangement, however, is very complicated andexpensive, since it requires a multiplicity of liquid crystal cells inorder to reduce the switching times. It is too expensive for wide use.

SUMMARY OF THE INVENTION

The objective of the present invention is to indicate an arrangement anda method for the electrical control of the intensity of non-polarizedlight, which at a low control voltage such as is available inconventional transistor circuits and integrated circuits, make possiblerapid controlling. In this context, a high switching efficiency shouldalso be achieved, i.e., a high transparency in the on-state and thehighest possible damping capacity of the supplied light in theoff-state. It should be possible to carry out the switchover of thelight at equally high efficiencies between different channels.

This objective is achieved in the arrangement according to the presentinvention as a result of the fact that a first reflecting device isconfigured for reflecting at least one of the polarized light bundles,so that the polarized light bundles proceed in parallel, that in thepath of the polarized light bundles at least one electro-opticalelement, that changes the polarization as a function of a suppliedcontrol voltage, and a second reflecting device for reflecting the lightbundles in the reverse direction are arranged such that the lightbundles pass through the at least one electro-optical element twice andare directed by the first reflecting device at the polarizing beamsplitter, and that the controlled light can be extracted from at leastone face of the polarizing beam splitter. In this context, provision isadvantageously made that the light bundles are reunited in the beamsplitter after passing through the remaining arrangement.

The arrangement according to the present invention can be used for therapid processing of gray-scale values and as a rapid optical switch at alow switching voltage and also as an active element for the automaticcontrol of light intensities in feedback loops having appropriate lightsources. It can be used in fiber-optic superstructures as well as inoptical parallel processors for processing messages.

The arrangement according to the present invention can also be used asan optical limiter in glasses, video cameras, or in optical messagetransmission. As a consequence of the small losses and high efficiency,applications are also possible for high-power laser light.

In contrast to the known electro-optical switches and modulators, thearrangement according to the present invention has many advantages. Theswitching efficiency for non-polarized light is more than 99% betweenthe two switching states. Losses, already in themselves minimal, canthrough anti-reflection layers be further reduced by the reflections inthe optical surfaces of the individual components in the arrangementaccording to the present invention.

In the arrangement according to the present invention, depending on thespecific embodiment, small angles of rotation of the optical indicatorof the liquid crystal are specifically required in the electrical field.As a result of this, an abundance of possibilities for the applicationof various electro-optical effects of liquid crystals is generated bythe arrangement according to the present invention. In particular, inthe application of liquid crystals having the SSFLC effect, switchingtimes can be achieved in the range of μs. The SSFLC effect is described,for example, in N. Clark et al., Appl. Phys. Lett. 36899 (1980); U.S.Pat. No. 4,563,059.

Using the arrangement according to the present invention, intermediatevalues can be arrived at in an advantageous manner between the on- andoff-state, so that a gray-scale value modulation having time constantsin the microsecond and submicrosecond range is possible through theapplication of the electroclinic effect.

Through the application of the DHF effect (deformed helix ferroelectriceffect) in the helix-shaped smectic C-phase, working voltage is ofroughly 1 V and time constants of roughly 10 μs can be achieved.

In addition, the arrangement according to the present invention has theadvantage that the switching efficiency is dependent on the color of thelight to only an extremely small degree. Therefore, the arrangementaccording to the present invention is also superbly suited for colorpictures. Finally, as a further advantage, the design of the arrangementaccording to the present invention is simple and cost-effective.

Most of the advantages of the arrangement according to the presentinvention rest on the fact that, as a result of the double passagethrough the electro-optical element, the electrical rotation of theindicator of the liquid crystal can be much smaller, even in connectionwith the delay plate, than in the case of a single passage, in order toachieve a desired rotational angle.

An advantageous specific embodiment of the arrangement according to thepresent invention consists in the fact that the electro-optical elementand the second reflecting device are separate components, provisionadvantageously being made that the at least one electro-optical elementis a liquid crystal cell having a liquid crystal layer betweentransparent electrodes, to which the control voltage can be supplied.

A further advantageous specific embodiment involving even less technicalexpense, consists in the fact that the electro-optical element is aliquid crystal cell having a liquid crystal layer between a transparentand a reflecting electrode, which form the second reflecting device, andthat the control voltage can be supplied to the electrodes.

In an advantageous refinement of the arrangement according to theinvention, provision is made that in the path of the parallel- runningpolarized light bundles, a delay plate is also arranged, the delay platehaving an optical intensity of one quarter of the wavelength of thelight or, in the case of broadband light, of the effective wavelength.

A further reduction of the rotational angle required for control ispossible in a refinement of the arrangement according to the presentinvention as a result of the fact that two electro-optical elements arearranged behind one another in the path of the parallel runningpolarized light bundles.

Depending on the specific preconditions and requirements, in thearrangement according to the present invention the first reflectingdevice can be configured in different ways. It should be noted that inthe use of two planar reflecting surfaces, which form a right angle, theline of intersection of the two surfaces is always parallel to apolarization plane of the polarized light bundles.

A further refinement of the arrangement according to the presentinvention consists in the fact that the at least one liquid crystal cellcontains a nematic liquid crystal. In this context, provision ispreferably made that the nematic liquid crystal has a positivedielectrical anisotropy and, in the electrical field, passes over into ahomeotropic orientation in a generally familiar manner.

This refinement can be configured such that thickness d of the liquidcrystal, without impingement by an electrical field, fulfills thecondition δn ·d=lambda/4+N·lambda with respect to its phase delay, Nbeing a whole number and δn being the birefringence of the liquidcrystal. However, it is also possible that thickness d of the liquidcrystal satisfies the condition δn·d=⅜·lambda+N·lambda or the conditionδn·d=lambda/2+N·lambda.

A further advantageous refinement of the arrangement according to thepresent invention consists in the fact that the least one liquid crystalcell contains a ferroelectric liquid crystal, thickness d of theferroelectric liquid crystal satisfying the conditionδn·d=lambda/4+N·lambda, the condition δn·d=(⅜) lambda+(N·lambda), or thecondition δn·d=(lambda/2)+(N·lambda).

The ferroelectric effect has the advantage that as a result of the smallrotational angles and of the rapid rotation of the slow axis, very shortswitching times can be achieved.

As already mentioned, the arrangement according to the present inventionis advantageously suited for the modulation or for the switching oflight. A switchover or a cross-fading between two output light bundlesis additionally possible in a further refinement through the fact thatthe first reflecting device, the electro-optical element, and the secondreflecting device are arranged such that light, that is controlledinversely to the light that can be extracted from the second face of thebeam splitter, emerges on the surface offset with respect to the lightto be controlled. Provision is also made that light bundles, that passthrough at the same surface of the beam splitter, have the samepreselected distance from each other in order to prevent reactions ofthe light bundles on the devices that are connected.

In the method according to the present invention, the objective isachieved through the fact that a first reflecting device for thereflection of at least one of the polarized light bundles is configuredso that the polarized light bundles run in parallel, that at least oneelectro-optical element is arranged in the path of the polarized lightbundles, the electro-optical element being penetrated by the beams ofthe light bundles and the polarization of the light bundles changing asa function of a supplied control voltage, that a second reflectingdevice changes the direction of the light bundles after they leave theelectro-optical element so as to run into themselves or to run inparallel and sends them once again to the electro-optical element, thatthe polarization of the light bundles is once again changed in theelectro-optical element, so that the sum of the changes of thepolarization of the light bundles, in the passage through the firstreflecting element, the subsequent passage through the electro-opticalelement, the subsequent reflection at the second reflecting element, thesecond passage through the electro-optical element, and the secondpassage through the first reflecting element, generates in the reversedirection an overall change of the polarization of the light bundles,the polarization depending on the control voltage at the electro-opticalelement, directing the light of the light bundles at the polarizing beamsplitter either to the input face—which corresponds to the polarizationstate that is in each case unchanged—or to the output face—whichcorresponds to the polarization state that is, in each case, orthogonal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(a) shows a first schematic diagram of the arrangement accordingto the present invention.

FIG. 1(b) shows a second schematic diagram of the arrangement accordingto the present invention.

FIG. 1(c) shows a third schematic diagram of the arrangement accordingto the present invention.

FIG. 1(d) shows a fourth schematic diagram of the arrangement accordingto the present invention.

FIG. 1(e) shows a fifth schematic diagram of the arrangement accordingto the present invention.

FIG. 1(f) shows a sixth schematic diagram of the arrangement accordingto the present invention.

FIG. 1(g) shows a seventh schematic diagram of the arrangement accordingto the present invention.

FIG. 1(h) shows an eighth schematic diagram of the arrangement accordingto the present invention.

FIG. 1(i) shows a ninth schematic diagram of the arrangement accordingto the present invention.

FIG. 1(j) shows a tenth schematic diagram of the arrangement accordingto the present invention.

FIG. 2(a) shows a first arrangement of two electro-optical switchesaccording to the related art in different operating states.

FIG. 2(b) shows a second arrangement of two electro-optical switchesaccording to the related art in different operating states.

FIG. 2(c) shows a first arrangement of an electro-optical switch thatoperates according to a similar principle to that of FIGS. 2(a) and2(b).

FIG. 2(d) shows a second arrangement of an electro-optical switch thatoperates according to a similar principle to that of FIGS. 2(a) and2(b).

FIG. 3(a) shows an exemplary embodiment of a device according to thepresent invention executed as an intermediate switch.

FIG. 3(b) shows a second exemplary embodiment of a device according tothe present invention executed as an intermediate switch.

FIG. 3(c) shows a third exemplary embodiment of a device according tothe present invention executed as an intermediate switch.

FIG. 3(d) shows a fourth exemplary embodiment of a device according tothe present invention executed as an intermediate switch.

FIG. 4(a) shows a first simplified arrangement sketch of a deviceaccording to the present invention for one channel.

FIG. 4(b) shows a second simplified arrangement sketch of a deviceaccording to the present invention for one channel.

FIG. 4(c) shows a third simplified arrangement sketch of a deviceaccording to the present invention for one channel.

FIG. 4(d) shows a fourth simplified arrangement sketch of a deviceaccording to the present invention for one channel.

FIG. 4(e) shows a first simplified arrangement sketch of a deviceaccording to the present invention for two channels.

FIG. 4(f) shows a second simplified arrangement sketch of a deviceaccording to the present invention for two channels.

FIG. 5(a) shows a first exemplary embodiment of the first reflectingdevice in a solely schematic representation of the electro-opticalelement and of the second reflecting device for one channel.

FIG. 5(b) shows a second exemplary embodiment of the first reflectingdevice in a solely schematic representation of the electro-opticalelement and of the second reflecting device for one channel.

FIG. 5(c) shows a third exemplary embodiment of the first reflectingdevice in a solely schematic representation of the electro-opticalelement and of the second reflecting device for one channel.

FIG. 5(d) shows a fourth exemplary embodiment of the first reflectingdevice in a solely schematic representation of the electro-opticalelement and of the second reflecting device for one channel.

FIG. 5(e) shows a fifth exemplary embodiment of the first reflectingdevice in a solely schematic representation of the electro-opticalelement and of the second reflecting device for one channel.

FIG. 5(f) shows a sixth exemplary embodiment of the first reflectingdevice in a solely schematic representation of the electro-opticalelement and of the second reflecting device for one channel.

FIG. 5(g) shows a seventh exemplary embodiment of the first reflectingdevice in a solely schematic representation of the electro-opticalelement and of the second reflecting device for one channel.

FIG. 5(h) shows an eighth exemplary embodiment of the first reflectingdevice in a solely schematic representation of the electro-opticalelement and of the second reflecting device for one channel.

FIG. 5(i) shows a first exemplary embodiment of the first reflectingdevice in a solely schematic representation of the electro-opticalelement and of the second reflecting device for two channels.

FIG. 5(j) shows a second exemplary embodiment of the first reflectingdevice in a solely schematic representation of the electro-opticalelement and of the second reflecting device for two channels.

FIG. 5(k) shows a third exemplary embodiment of the first reflectingdevice in a solely schematic representation of the electro-opticalelement and of the second reflecting device for two channels.

FIG. 5(l) shows a fourth exemplary embodiment of the first reflectingdevice in a solely schematic representation of the electro-opticalelement and of the second reflecting device for two channels.

FIG. 5(m) shows a fifth exemplary embodiment of the first reflectingdevice in a solely schematic representation of the electro-opticalelement and of the second reflecting device for two channels.

FIG. 5(n) shows a sixth exemplary embodiment of the first reflectingdevice in a solely schematic representation of the electro-opticalelement and of the second reflecting device for two channels.

FIG. 6(a) shows a first exemplary embodiment for the second reflectingdevice in a solely schematic representation of the electro-opticalelement and of the first reflecting device for one channel.

FIG. 6(b) shows a second exemplary embodiment for the second reflectingdevice in a solely schematic representation of the electro-opticalelement and of the first reflecting device for one channel.

FIG. 6(c) shows a third exemplary embodiment for the second reflectingdevice in a solely schematic representation of the electro-opticalelement and of the first reflecting device for one channel.

FIG. 6(d) shows a fourth exemplary embodiment for the second reflectingdevice in a solely schematic representation of the electro-opticalelement and of the first reflecting device for one channel.

FIG. 6(e) shows a fifth exemplary embodiment for the second reflectingdevice in a solely schematic representation of the electro-opticalelement and of the first reflecting device for one channel.

FIG. 6(f) shows a sixth exemplary embodiment for the second reflectingdevice in a solely schematic representation of the electro-opticalelement and of the first reflecting device for one channel.

FIG. 6(g) shows a seventh exemplary embodiment for the second reflectingdevice in a solely schematic representation of the electro-opticalelement and of the first reflecting device for one channel.

FIG. 6(h) shows an eighth exemplary embodiment for the second reflectingdevice in a solely schematic representation of the electro-opticalelement and of the first reflecting device for one channel.

FIG. 6(i) shows a ninth exemplary embodiment for the second reflectingdevice in a solely schematic representation of the electro-opticalelement and of the first reflecting device for one channel.

FIG. 6(j) shows a tenth exemplary embodiment for the second reflectingdevice in a solely schematic representation of the electro-opticalelement and of the first reflecting device for one channel.

FIG. 6(k) shows an eleventh exemplary embodiment for the secondreflecting device in a solely schematic representation of theelectro-optical element and of the first reflecting device for onechannel.

FIG. 6(l) shows a twelvth exemplary embodiment for the second reflectingdevice in a solely schematic representation of the electro-opticalelement and of the first reflecting device for one channel.

FIG. 6(m) shows a thirteenth exemplary embodiment for the secondreflecting device in a solely schematic representation of theelectro-optical element and of the first reflecting device for onechannel.

FIG. 6(n) shows a fourteenth exemplary embodiment for the secondreflecting device in a solely schematic representation of theelectro-optical element and of the first reflecting device for onechannel.

FIG. 6(o) shows a first exemplary embodiment for the second reflectingdevice in a solely schematic representation of the first reflectingdevice and of the electro-optical element for two channels.

FIG. 6(p) shows a second exemplary embodiment for the second reflectingdevice in a solely schematic representation of the first reflectingdevice and of the electro-optical element for two channels.

FIG. 6(q) shows a third exemplary embodiment for the second reflectingdevice in a solely schematic representation of the first reflectingdevice and of the electro-optical element for two channels.

FIG. 6(r) shows a fourth exemplary embodiment for the second reflectingdevice in a solely schematic representation of the first reflectingdevice and of the electro-optical element for two channels.

FIG. 6(s) shows a fifth exemplary embodiment for the second reflectingdevice in a solely schematic representation of the first reflectingdevice and of the electro-optical element for two channels.

FIG. 6(t) shows a sixth exemplary embodiment for the second reflectingdevice in a solely schematic representation of the first reflectingdevice and of the electro-optical element for two channels.

FIG. 6(u) shows a seventh exemplary embodiment for the second reflectingdevice in a solely schematic representation of the first reflectingdevice and of the electro-optical element for two channels.

FIG. 6(v) shows an eighth exemplary embodiment for the second reflectingdevice in a solely schematic representation of the first reflectingdevice and of the electro-optical element for two channels.

FIG. 6(w) shows a ninth exemplary embodiment for the second reflectingdevice in a solely schematic representation of the first reflectingdevice and of the electro-optical element for two channels.

FIG. 6(x) shows a tenth exemplary embodiment for the second reflectingdevice in a solely schematic representation of the first reflectingdevice and of the electro-optical element for two channels.

FIG. 6(y) shows an eleventh exemplary embodiment for the secondreflecting device in a solely schematic representation of the firstreflecting device and of the electro-optical element for two channels.

FIG. 6(z) shows a twelfth exemplary embodiment for the second reflectingdevice in a solely schematic representation of the first reflectingdevice and of the electro-optical element for two channels.

FIG. 6(za) shows a thirteenth exemplary embodiment for the secondreflecting device in a solely schematic representation of the firstreflecting device and of the electro-optical element for two channels.

FIG. 7(a) shows a first exemplary embodiment in a perspectiverepresentation.

FIG. 7(b) shows a second exemplary embodiment in a perspectiverepresentation.

FIG. 7(c) shows a third exemplary embodiment in a perspectiverepresentation.

FIG. 7(d) shows a fourth exemplary embodiment in a perspectiverepresentation.

FIG. 8(a) shows a first exemplary embodiment for one channel havingspecifically one prism as a reflecting device, one nematic liquidcrystal cell, and one delay plate in two operating states.

FIG. 8(b) shows a second exemplary embodiment for one channel havingspecifically one prism as a reflecting device, one nematic liquidcrystal cell, and one delay plate in two operating states.

FIG. 8(c) shows a first exemplary embodiment as in FIGS. 8(a) and(b),however without a delay plate.

FIG. 8(d) shows a second exemplary embodiment as in FIGS. 8(a) and(b),however without a delay plate.

FIG. 8(e) shows a first exemplary embodiment as in FIGS. 8(a) and (b),however having a ferroelectric liquid crystal cell.

FIG. 8(f) shows a second exemplary embodiment as in FIGS. 8(a) and(b),however having a ferroelectric liquid crystal cell.

FIG. 8(g) shows a first embodiment for two channels having prisms asreflecting devices, one nematic liquid crystal cell, and one delay platein two operating states.

FIG. 8(h) shows a second embodiment for two channels having prisms asreflecting devices, one nematic liquid crystal cell, and one delay platein two operating states.

FIG. 8(i) shows a first exemplary embodiment as in FIGS. 8(g) and (h),however having a ferroelectric liquid crystal cell.

FIG. 8(j) shows a second exemplary embodiment as in FIGS. 8(g) and (h),however having a ferroelectric liquid crystal cell.

FIG. 9(a) shows the switching time and the angle of inclination of theelectroclinic material as a function of temperature.

FIG. 9(b) shows the modulation loop of an arrangement for a channel as afunction of the control voltage.

FIG. 9(c) shows the modulation loop of an arrangement for two channelsas a function of the control voltage.

In the Figures, the same parts are given the same reference numerals. Inthe Figures, the light bundles are represented as straight lines havingarrows pointing in the longitudinal direction, the arrows indicating thedirection of propagation of the specific light bundle. Double arrowstransverse to the longitudinal direction indicate a polarization in thedrawing plane (p), whereas circles having a period represent apolarization perpendicular to drawing plane (s).

FIG. 2 represents a known electro-optical switch in a closed position(FIGS. 2 (a) and 2(c) and in an open position (FIGS. 2(b) and 2(d).

In FIGS. 2(a) and 2(b), the non-polarized light bundle to be switched isfed to a polarizing beam splitter 1 via an input face 1 a. Beam splitter1 switches the non-polarized collimated light at the input face into itspolarized components s and p, which leave the polarizing beam splitteras light bundles 2, 3. Polarized light bundles 2, 3 are directed in thedirection of a TN liquid crystal cell 104 by a mirror 102, 103,respectively. The reflected light bundles pass through liquid crystalcell 104 in the opposite direction and are reflected back to thepolarizing beam splitter by the respective other mirror 103, 102.

If no voltage is applied to the electrodes of the liquid crystal cell,the latter rotates the polarization plane of the light bundles in eachcase by 90°. This is represented in FIG. 2(a). Light bundle 2, which isinitially polarized perpendicular to the drawing plane, thus receives apolarization in the drawing plane and is thus directed via mirror 103 tothe polarizing beam splitter. Due to this polarization, this beam bundleis not reflected in the beam splitter, but rather is permitted to passstraight through in the direction of the entrance beam.

Light which is initially polarized in the drawing plane is rotatedperpendicular to the drawing plane and arrives at beam splitter 1 viamirror 103, where it is reflected in the direction of the light bundlethat has been sent. At an output face 1 b, no light emerges.

In the case represented in FIG. 2(b), liquid crystal cell 104 is actedupon by voltage and does not rotate the polarization plane. Thuspolarized light bundles 2,3 arrive at beam splitter 1, in each case,having a polarization that is rotated with respect to the arrow in FIG.2(a). There, returning light bundle 2 is reflected, and returning lightbundle 3 is not reflected, so that both light bundles emerge from outputface 1 b.

FIGS. 2(c) and 2(d) depict an electro-optical switch that operatesaccording to a similar principle, sending light that strikes beamsplitter 1 from the various channels E, E′ to various outputs A, A′.Since the angle of inclination of liquid crystal cells 104′, 104″ usedis limited given the high switching frequencies, a plurality of cells isnecessary in order to make possible a complete rotation of thepolarization planes of the light bundles. In the closed positionaccording to FIG. 2(c), the light bundle of channel E is conveyed tochannel A via a second beam splitter 1′. The light from channel E′arrives at channel A. In the open position according to FIG. 2(d), onthe other hand, the light bundles are switched via a cross, so thatchannels E and A′ as well as E′ and A are connected to each other.

FIGS. 1(a) and 1(b) show two variants of a first exemplary embodiment,in which the light bundle to be controlled is fed via input face 1 a ofpolarizing beam splitter 1 and is first split into two polarized lightbundles 2 and 3 as in the known arrangement according to FIGS. 2(a) and2(b). In a first reflecting device 4, polarized light bundles 2, 3 arethen deflected such that they run in parallel. From there they arrive ata device 5, which contains an electro-optical element 6, which rotatesthe polarization as a function of a supplied control voltage. A secondreflecting device is configured in various ways in FIGS. 1(a) and 1(b),namely such that, in the case of FIG. 1(a), each of parallel-runningpolarized light bundles 2, 3 is reflected back into itself, whereas, inthe case of FIG. 1(b), light bundle 2 is reflected as light bundle 2′opposite to light bundle 3, and light bundle 3 is reflected as lightbundle 3′ opposite to light bundle 2. Both variants are depicted in theon-state.

FIGS. 1(c) through 1(j) show the same arrangement as a changeover switchfrom an input channel E or E′ to two output channels A, A′,respectively, in different switching states and having differentconfigurations of schematically represented second reflecting device 7.In this context, the light bundle is introduced somewhat offset from thecenter of beam splitter 1, so that the beam path no longer runssymmetrically, and controlled light bundles 2′ and 3′ are sent from beamsplitter 1 to the one output A or to the other output A′ depending onthe polarization direction. The deflection of the beam path inreflecting devices 4, 7 can be realized in the most various ways; theparticular ways may be selected for this purpose depending on theconcrete requirement. In FIGS. 5 and 6, examples are given.Electro-optical element 6, in the examples, is acted upon by a controlvoltage via connection terminals 6′ and 6″.

A further application case for the arrangement according to the presentinvention in accordance with the FIGS. 1(c) through 1(j) is depicted inFIGS. 3(a) through 3(d) in two specific configurations, each in twoswitching states. The arrangement is used as a cross switch among fourchannels. In accordance with the switching state, each input E, E′ isconnected to one output A, A′, respectively.

In FIG. 4(a), electro-optical element 6 is depicted in somewhat greaterdetail than liquid crystal cell 8 having a liquid crystal 9 betweentransparent electrodes 9′, 9″ and a narrow 8′, which designates the slowaxis. On the other hand, the exemplary embodiment according to FIG. 4(b)contains a delay plate 10.

In the exemplary embodiment depicted in FIG. 4(c), provision is made fora further liquid crystal cell 11 having a liquid crystal 12 andtransparent electrodes 12′ and 12″. By placing behind one another twoliquid crystal cells 8, 11, in contrast to the exemplary embodiments inaccordance with FIGS. 4(a) and 4(b), only half of the rotation isrequired for achieving the same intensity differential in the controlledlight bundle. As will be explained in detail below, under certainpreconditions, an angle of +/−5.625° is sufficient for fully advancedcontrol.

FIGS. 4(d) through 4(f) show embodiments of the same arrangement as thecross changeover switch.

FIGS. 5(a) through 5(h) show exemplary embodiments having differentvariants of first reflecting device 4, which is executed in FIG. 5(a) asa mirror. In the exemplary embodiment according to FIG. 5(b), fordeflecting the polarized light bundles in parallel directions, twomirrors 14, 15 are used. In the exemplary embodiment according to FIG.5(c), one polarized light bundle 3 is deflected in the direction ofother light bundle 2 with the assistance of a prism 16, whereas, forthis purpose, in the exemplary embodiment according to FIG. 5(d), twoprisms 17, 18 are used. These prisms in the exemplary embodimentaccording to FIG. 5(e) are each joined to a partial prism of thepolarizing beam splitter to make one body. This has the advantage thatno losses can occur through reflections on the border surfaces thatotherwise exist between beam splitter 1 and prisms 17, 18. In addition,in the exemplary embodiment according to FIG. 5(e), assembly costs aresaved.

In the exemplary embodiments according to FIGS. 5(f) through, 5(h),which each depict three views, the supplied light bundle as well as thecontrolled light bundle each lie in a plane parallel to liquid crystalcell 6 and to second reflecting device 7. Both polarized light bundlesemerging from the polarized beam splitter are deflected (FIG. 5(f)) inthe direction of electro-optical element 6 with the assistance ofmirrors 19, 20. This takes place in the exemplary embodiment accordingto FIG. 5(g) with the assistance of two prisms 21, 22. In addition, inFIG. 5(g), the angle of rotation of 22.5° between the negative and apositive voltage is depicted with respect to liquid crystal cell 6,which in this case contains a ferroelectric liquid crystal. In theexemplary embodiment according to FIG. 5(h), pentaprisms 23, 24 are usedfor deflection in polarized light bundles 2, 3.

FIGS. 5(i) through 5(n) each depict the beam paths of the samearrangements, if they are acted upon, in each case, by two inputs E, E′and two outputs A, A′. In this configuration, the arrangements can againbe used as changeover switches.

FIGS. 6(a) through 6(g) depict exemplary embodiments for secondreflecting device 7, whereas first reflecting device 4 andelectro-optical element 6 are not indicated in greater detail. FIG. 6(a)depicts a mirror 25 as a second reflecting device, whereas secondreflecting device in FIG. 6(b) is formed by a hollow triple mirror 26,which is composed of three planar mirrors 27, 28, 29.

The exemplary embodiment according to FIG. 6(c) includes two such triplemirrors 30, 31, which are composed of three planar mirrors 32, 33, 34and 35, 36, 37, respectively. In FIG. 6(c), it is also indicated that inthe arrangement according to the present invention is not absolutelynecessary to reflect the parallel polarized light bundles in themselvesor in the respective other light bundle.

The exemplary embodiment according to FIG. 6(d) contains a massivetriple mirror as the second reflecting device, and the exemplaryembodiment according to FIG. 6(e) contains two massive triple mirrors39, 40.

The exemplary embodiment according to FIG. 6(d) contains a pyramid prismas the second reflecting device; the exemplary embodiment according toFIG. 6(e) contains two pyramid prisms 39, 40.

FIG. 6(f) depicts two mirrors 41, 42, which form an angle of 90° andwhich reflect each of the parallel polarized light bundles into theother one. In the exemplary embodiment according to FIG. 6(g), provisionis made for two pairs of mirrors 43, 44, which are composed of twoindividual mirrors 45, 46 and 47, 48, respectively.

FIG. 6(h) depicts an example for measures to obtain the same opticalpath lengths for polarized light bundles 2, 2′, 3, 3′. Supplemental pathlength 49 of light bundle 3, 3′ is compensated for through the fact thatmirror pair 44 is arranged so as to be closer to electro-optical element6 than mirror pair 43. Distance 50 corresponds exactly to path lengthdifferential 49.

The optical path lengths of both light bundles are the same in theexemplary embodiment according to FIG. 6(i) on account of thesymmetrical design. As a second reflecting device, a 90° prism 51 isused. In the otherwise identical design, the exemplary embodimentaccording to FIG. 6(j) includes two 90° prisms 52, 53 as the secondreflecting device.

The exemplary embodiment according to FIG. 6(k) contains as the firstreflecting device a prism 16, a path length differential 54, in turn,resulting between the two polarized light bundles. This is compensatedfor by an offset shift 55 of prisms 52, 53 that function as the secondreflecting device.

In the case of the arrangement according to FIG. 6(l), provision is madefor two pentaprisms 56, 57 as the second reflecting device in asymmetrical design of the entire arrangement. In this context, firstreflecting device 4, which is only schematically represented in FIG.6(l), is formed, for example, by two mirrors and prisms corresponding tothe exemplary embodiment according to FIGS. 5(b), 5(d), or 5(e).

In the exemplary embodiment according to FIG. 6(m), provision is madefor two ridge prisms 58, 59 as second reflecting device 7, which forillustrative purposes are depicted a second time in a different view.The exemplary embodiment according to FIG. 6(n) contains two ridgemirror systems 60, 61, which are composed of two individual mirrors 62,63 and 64, 65, respectively.

The corresponding application forms as changeover switches can be foundin FIGS. 6(o) through 6(za), the exceptional feature arising in FIGS.6(p) and 6(r), that mirrors 66, 67 and prism 68 are arranged verticallyand, as a result, cause a transverse offset of the light bundles. Thiscan present advantages in the spatial disposition of the device in aconcrete application.

FIG. 7(a) depicts a three-dimensional representation of an exemplaryembodiments in the form of an exploded view. A prism 16 functions as afirst reflecting device, a mirror 25 as a second. Angle α is the anglebetween slow axis 8′ of liquid crystal 9 and the s-polarization ofbundle 2. Angle β is the angle between rapid axis 10′ of delay plate 10(on a lambda/4 plate) and the s-polarization of light bundle 2.

In the exemplary embodiment of FIG. 7(b) designed so as to otherwisecorrespond to FIG. 7(a), provision is made for a triple mirror 38 as thesecond reflecting device. In this way, the polarized light bundles thatare reflected so as to run in parallel are reversed with respect to thenon-reflected light bundles, so that altogether for both light bundlesthe same optical path results. This also applies to the exemplaryembodiment according to FIG. 7(c), in which a 90° prism 51 is arrangedas the second reflecting device.

FIG. 7(d) depicts the arrangement according to FIG. 7(c) for theapplication case as changeover switch.

FIGS. 8(a) and 8(b) depict an exemplary embodiment having a 90° prism 16as a first reflecting device, a liquid crystal cell, and a lambda/4plate 10 as an electro-optical element 6. In addition, a 90° prism 51 isprovided as a second reflecting device. FIG. 8(a) represents thearrangement in the off-state, i.e., closed, whereas FIG. 8(b) depictsthe device in the on-state, or open.

The exemplary embodiment according to FIGS. 8(a) and (b) contains anematic liquid crystal cell having a positive dielectrical anisotropy. nis the pneumatic director, which corresponds to switchable optical axis8′. Light bundles 2″ and 3″ at this angle have a polarization of 45° and−45° In lambda/4 plate 10, this linear polarization is transformed intoa right or left rotating circular polarization, which after thereflection in prism 51 obtains a different direction of rotation.

In the repeated passage through lambda/4 plate 10, a linear polarizationagain arises of −45° regarding light bundle 2′″, and of +45° regardinglight bundle 3′″. This polarization, in the repeated passage through theliquid crystal cell, is rotated by 45°, so that light bundle 2′ ispolarized in the drawing plane, whereas light bundle 3′ is polarizedperpendicular to the drawing plane. In this polarization, light bundle2″ is permitted to pass directly through polarizing beam splitter 1,whereas light bundle 3″ after the deflection in prism 16 is reflected inpolarizing beam splitter 1 and emerges through input face 1 a. Thus nolight arrives through output face 1 b, so that in the describedvoltageless case according to FIG. 8(a), the switch is closed. Through acorresponding transmission of the light from input face 1 a or through acorresponding arrangement of sensors, the arrangement according to FIGS.8(a) and 8(b) can also be used as a changeover switch or, in the case ofa gradual transition, as cross-fader.

In the case depicted in FIG. 8(b), liquid crystal cell 8 is acted uponby a voltage, so that the nematic liquid crystal is placed into thehomeotropic state. The non-polarized light at input face 1 a is conveyedto output face 1 b. Director 8″ of nematic liquid crystal 9 isperpendicular to the surface of the electrodes.

FIGS. 8(c) and 8(d) depict an exemplary embodiment having aferroelectric liquid crystal cell 8 of a thickness of the liquid crystallayer, which effects an optical path differentiation of (⅜) lambda inthe blocking state according to FIG. 8(c). Prism 16 is used as a firstreflecting device, a 90° prism 51 as a second reflecting device. Inorder to switch from the off-state in the on-state, the polarity of thevoltage at electrodes 9′, 9″ is reversed. In the off-state (closed),light bundles 2″ and 3″ emerging from liquid crystal cell 8 areelliptically polarized. Through the reflection in prism 51, thedirection of rotation and the angle of the axes of ellipsis are changed.In the off-state in accordance with FIG. 8(d), no rotation ofpolarization takes place by liquid crystal cell 8.

The exemplary embodiment according to FIGS. 8(e) and 8(f) contains aferroelectric liquid crystal cell, whose liquid crystal layer 9 has athickness d such that the optical path differential is lambda/2. Inaddition, a lambda/4 plate 10 is used. In the pass-through stateaccording to FIG. 8(e), slow axis 8′ is positioned as the polarizationplane of light bundle 3. In the blocking state according to FIG. 8(f),slow axis 8′ is offset by 22.5° from the polarization plane of lightbundle 3. Prism 16 and prism 51 are employed as a first and secondreflecting device is as in the exemplary embodiment according to FIG.8(c) and 8(d).

FIGS. 8(g) through 8(j) depict the beam path of the arrangements,described above, in their use as changeover switches.

FIG. 9(a) depicts the temperature dependency of the induced angle ofinclination +/−θ and of average switching time tau for electroclinicmaterial FLC-392. The thickness of the liquid crystal cell is 1.6 μm,the control voltage is +/−10 V. FIG. 9(b) represents the modulationdepth of an arrangement according to FIGS. 7(c) and 8(e/f) as a functionof control voltage V. A liquid crystal cell having an electroclinicliquid crystal and a lambda/4 plate is based on the measurement.

FIG. 9(c) depicts intensity I of the controlled light arriving atoutputs A, A′ as a function of control voltage U_(s). The curves wereincluded in the arrangement according to FIG. 7(d). In the upperdiagram, the light comes from input E and in the lower diagram frominput E′. It is clear that a complete switchover between outputs A andA′ takes place using liquid crystal cell FLC 392 used here at a voltagedifferential of roughly 60 volts.

Through the type of liquid crystal and its drive, through the thicknessof the liquid crystal, through the arrangement of a delay plate andfurther optical preconditions in the arrangement according to thepresent invention, a great many different combinations are possible.Some of them are described below.

If, for example, in the nematic liquid crystal the transformation isundertaken from planar to homeotropic, then a use in binary switchingprocesses (on/off) is given. For this case, the orientation of slow axis8′ coincides with the director of the long molecular axis. It is to bebelow 45° with respect to the polarization directions of the polarizingbeam splitter. In this context, thickness d of the liquid crystal layeris to satisfy the condition δn·d=lambda/4+N·lambda, where N=0, +/−1,+/−2, +/−3, . . . In this context, δn is the birefringence of the layer(δn=n_(L)-n_(S)), n_(L) being the refractive index of the liquid crystalin the slow axis and n_(s) in the rapid axis. Without an electricalfield, the switch is in the off-state. With an electrical field, theliquid crystal is homeotropic and the light enters at face 1 b(on-state). Examples for such arrangements are depicted in FIGS. 6(b)through 6(e) and 7(b).

In the designs according to FIGS. 6(f) through 6(n), the properties ofthe liquid crystal are different than in the preceding fields. First ofall, thickness d of the liquid crystal cell is such that a delay ofδn·d=(⅜) lambda+N·lambda results. In addition, the director of the layerof 22.5° is switched over to −22.5° in the electrical field with respectto the p-polarization plane. Without an electrical field, thearrangement is switched off. With an electrical field, a homeotropicorientation begins, the arrangement being switched on.

Liquid crystal cells combined with the use of the s-effect in nematicliquid crystals can be used for switches of a high aperture and havingswitching times in the order of magnitude of ms, i.e., in a frequencyrange of 0 Hz to 100 Hz, preferably using a lambda/4 plate.

The SSFLC-effect (surface stabilized ferroelectric liquid crystals) canbe used for two different angles of inclination in chiral, smectic, andferroelectric phases of the liquid crystal. The FLC material having theangle of inclination 22.50 can be used without a delay plate in thespecific embodiments according to FIGS. 6(a) through 6(e). Thickness dof the liquid crystal for both polarities of the voltage appliedsatisfies the condition δn·d=lambda/4+N·lambda. The orientation of thenormal of the smectic positions (direction of friction) is to have anangle of +22.5° or −22.5° with respect to the polarization direction ofthe s- or p-light bundle 2, 3. For the one field polarity, light emergesfrom the output face, for the other field polarity it does not. For theexemplary embodiments in FIGS. 6(a) and 7(a), the polarity has areversed sign in comparison to FIGS. 6(b) through 6(e) and 7(b).

For the exemplary embodiments according to FIGS. 6(f) through 6(n),7(c), 8(c/d), and 8(e/f), the optical properties of the liquid crystalare different than in the case described above. The FLC positions are tohave a delay of (⅜) lambda+N·lambda. The value of the switching angle isonly 11.25°. The normal for the smectic position of the FLC material isto have the angle+11.25° or −11.25° or+33.75° or−33.75° with respect tothe p-polarization direction of light bundle β. The arrangements of thistype can be used for switching times between 10 μs and 20 μs andvoltages between 20 volts and 30 volts.

The electroclinic effect and the DHF effect (deformed helixferroelectrics) are used in arrangements according to the presentinvention for the optical modulation using intermediate values.

For the exemplary embodiments according to FIGS. 6(a) through 6(e),7(a), and 7(b), the orientation of the normal of the smectic positionsis to form an angle of +45° or −45° with the s- or p-polarization plane.The thickness of the liquid crystal layer is to permit the delaylambda/4+N·lambda. The light intensity permitted to pass through fromface 1 a to face 1 b of the polarizing beam splitter continually variesfrom 0% to 100%, if the electrically induced angle of inclination of theslow axis of the indicator varies between 0° and45°. For the case inwhich the DHF effect is used, the necessary axis tilt is +/−22.5°, whichcan be achieved using a few volts of control voltage. The switchingtime, in this context, is roughly 100 μs. Appropriate liquid crystalcells are described, for example, in: L. A. Beresnev et al: “DeformedHelical Ferroelectric Liquid Crystal Display: a New Electro-optical Modein Ferro Electrical Liquid Crystals,” Liquid Crystals, Volume 5, p.1171-1179 (1989) and in L. A. Beresnev et al: “Ferroelectric LiquidCrystal Displays,” Swiss Patent 3722/87.

In the exemplary embodiments according to FIGS. 6(f) through 6(n), 7(c),8(c/d), 8(e/f), the angle of inclination of slow axis 8′ is only 11.25°in the electrical field. For this purpose, a very rapid electroclinicmaterial having switching times of a few μs is used, as is made known,for example, in U.S. Pat. No. 4,838,663. These exemplary embodimentspermit a continual modulation of non-polarized light between 0% and 100%at a control voltage in the range of+/−30 volts.

An advantageous arrangement according to the present invention includesa ferroelectric liquid crystal cell and a lambda/4-plate, which isdepicted in FIGS. 4(b), 7(a) through 7(c), 8(c/d), and 8(e/f). In thiscontext, there is an abundance of possibilities to for realizing theorientation of slow axis 8′ of liquid crystal layer 8 and of the rapidaxis 10′ of delay plate 10 around the off- and on-state of thearrangement. This is depicted in FIG. 8(e/f).

In the on-state, polarization directions of light bundles 2, 3 areoriented parallel or perpendicular to the slow axis of the liquidcrystal and of delay plate 10. As a result, the light is not changedwith respect to its polarization state either in the liquid crystal cellor in the delay plate. Second reflecting device 7 also does not alterthe polarization state, so that the light of both polarizationdirections reaches output face 1 b of polarizing beam splitter 1.

In the off-state, the director (indicator orientation) of liquid crystal9 tilts 22.5° as a result of the effect of the electrical field. Sincethe delay in the liquid crystal is equal to lambda/2, the liquid crystalcell rotates the polarization direction 2·22.5°=45°. After lambda/4plate 10, light that is circularly polarized is obtained, which isreflected by second reflecting device 7 so as to be circularlypolarized, the direction of rotation being reversed. After the secondpassage through lambda/4 plate 10, light is obtained that is polarizedin light bundle 2′″ or 3′″ in a linear fashion, and that is polarized(−45°) after the first passage through the liquid crystal cell so as tobe orthogonal with respect to the light of light bundles 2″ and 3′.These light bundles are rotated in the second passage through the liquidcrystal cell by 2·(45°+22.5°)=(90°+45°) and thus achieve the respectiveorthogonal orientation 2′, 3′ of the polarization. Polarizing beamsplitter 1 unites the light bundles in face 1 b.

In the cases of the electroclinic effect and of the DHF effect, theelectrically controlled permeability of the arrangement according topresent invention between faces 1 a and 1 b of polarizing beam splitter1 for non-polarized light between the values 0% and nearly 100% cancontinually be changed. Applications include rapid optical limiters orthe rapid automatic control of light intensities. In this context, lightdetectors may be located at the output of the arrangement which exercisea control function on the electrodes of the liquid crystal cell throughelectrical feedback. Applications, by way of example, are described inSwiss Patent No. 888 102 583 and European Published Patent ApplicationNo. 0 335 056, as well as in M. Eve et al: “New Automatic-gain-controlSystem Optical Receivers,” Electronics Letter 15, pp. 146-147 (1979).

The electrically adjustable angles of inclination can be halved in thearrangement according to the present invention if two liquid crystalcells are arranged behind one another. In the electroclinic effect, theextremely small angle of inclination of +/−5.6250 is required in orderto switch light through at switching times of 1 μs and working voltagesof +/−10 V. Rapid electroclinic liquid crystal materials havingswitching times of 1 μs and, among them in low working voltages, arecomposed of mixtures of a lamellar matrix, for example of a smectic A-or C-phase and chiral doping molecules having an angle of inclination ofΘm, and they are known, for example, from German Published PatentApplication 196 24 769. Experiments have shown that time constants of100 ns at control voltage is of 10 volts to 20 volts at roomtemperatures can be achieved. FIG. 9(c) indicates intensity I of thecontrolled light arriving at outputs A, A′ as a function of the controlvoltage. The curves were included in an arrangement according to FIG.7(d). In the upper diagram, the light comes from input E and in thelower diagram from input E′. It is clear that a complete switchoverbetween outputs A and A′ takes place using the liquid crystal cellFLC-392 used here at a voltage differential of roughly 60 V.

What is claimed is:
 1. An arrangement for achieving an electricalcontrol of an intensity of a non-polarized light, comprising: a beamsplitter for splitting a supplied light into a plurality of polarizedlight bundles that are orthogonal with respect to each other; adownstream first reflecting device for parallelizing each one of theplurality of polarized light bundles; a plurality of transparentelectrodes; a plurality of electrically controllable liquid crystalcells that are connected behind one another, wherein: the plurality ofelectrically controllable liquid crystal cells are embedded between theplurality of transparent electrodes, and the plurality of electricallycontrollable liquid crystal cells alter a polarization of the pluralityof polarized light bundles as a function of a control voltage that isapplied to the plurality of transparent electrodes; and at least onedownstream second reflecting device arranged to reflect the plurality ofpolarized light bundles in an opposite direction such that the pluralityof polarized light bundles pass through the plurality of electricallycontrollable liquid crystal cells a second time and subsequently are atleast partially reunited by the first reflecting device and the beamsplitter depending on the polarization and are fed to at least oneoutput location where the electrically controlled light can beextracted.
 2. The arrangement according to claim 1, wherein, withrespect to the beam splitter, a last one of the plurality of transparentelectrodes of the plurality of electrically controllable liquid crystalcells, in a formation of the at least one second reflecting device,exhibits one of a reflecting characteristic and a reflecting coating. 3.The arrangement according to claim 1, further comprising: a phase delayplate having an optically effective thickness of one quarter of anaverage wavelength of the light to be controlled and being arranged in apath of the parallelized plurality of polarized light bundles.
 4. Thearrangement according to claim 1, wherein: the first reflecting deviceis configured so as to reduce a design length of the arrangement suchthat the plurality of polarized light bundles run perpendicular to aplane created by at least one of the plurality of polarized lightbundles to be controlled and another one of the plurality of polarizedlight bundles that is controlled.
 5. The arrangement according to claim1, wherein: the plurality of electrically controllable liquid crystalcells include nematic liquid crystals having a positive dielectricalanisotropy, a thickness d of each of the nematic liquid crystalssatisfies one of the conditions of δn·d=lambda/4+N·lambda,δn·d=⅜·lambda+N·lambda, and δn·d=lambda/2+N·lambda, and N is a wholenumber and δn is a birefringence of the nematic liquid crystals.
 6. Thearrangement according to claim 1, wherein: the plurality of electricallycontrollable liquid crystal cells include ferroelectric liquid crystals,a thickness d of each one of the ferroelectric liquid crystals satisfiesone of the conditions of δn·d=lambda/4+N·lambda, δn·d=⅜ lambda+N·lambda,and δn·d=lambda/2+N·lambda, and N is a whole number and on is abirefringence of the ferroelectric liquid crystals.
 7. The arrangementaccording to claim 1, further comprising: a plurality of electro-opticalelements arranged behind one another in a path of the parallelizedplurality of polarized light bundles.
 8. The arrangement according toclaim 7, wherein: the plurality of electro-optical elements include aferroelectric liquid crystal.
 9. The arrangement according to claim 8,wherein: a thickness d of the ferroelectric liquid crystal satisfies thecondition δn·d=lambda/4+N lambda.
 10. The arrangement according to claim8, wherein: a thickness d of the ferroelectric liquid crystal satisfiesthe condition δn·d=(⅜) lambda+(N·lambda).
 11. The arrangement accordingto claim 8, wherein: a thickness d of the ferroelectric liquid crystalsatisfies the condition δn·d=(lambda/2)+(N·lambda).
 12. The arrangementaccording to claim 1, wherein: the first reflecting device includes amirror.
 13. The arrangement according to claim 12, wherein: the mirrorcorresponds to a dielectrical mirror.
 14. The arrangement according toclaim 1, wherein: the first reflecting device is a hollow ridge prism.15. The arrangement according to claim 1, wherein: the first reflectingdevice is a massive ridge prism.
 16. The arrangement according to claim15, wherein: the massive ridge prism includes a reflecting surface onwhich is arranged a metal mirror.
 17. The arrangement according to claim1, wherein: the first reflecting device includes a plurality of mirrors.18. The arrangement according to claim 17, wherein: the first reflectingdevice includes another plurality of mirrors arranged such that theplurality of polarized light bundles run perpendicular to a plane formedby at least one of the plurality of polarized light bundles to becontrolled and another one of the plurality of polarized light bundlesthat is controlled.
 19. The arrangement according to claim 1, wherein:the first reflecting device includes a 90° prism.
 20. The arrangementaccording to claim 19, wherein: the first reflecting device includes aplurality of other 90° prisms arranged such that the plurality ofpolarized light bundles run perpendicular to a plane formed by at leastone of the plurality of polarized light bundles to be controlled andanother one of the plurality of polarized light bundles that iscontrolled.
 21. The arrangement according to claim 20, wherein: the beamsplitter and at least one of the 90° prisms and the plurality of other90° prisms form one unit.
 22. The arrangement according to claim 1,wherein: the first reflecting device includes a plurality of 90° prisms.23. The arrangement according to claim 1, wherein: the first reflectingdevice and the beam splitter include a first prism and a second prismseparated from each other by a polarizing layer.
 24. The arrangementaccording to claim 1, wherein: the first reflecting device includes aplurality of hollow ridge mirrors.
 25. The arrangement according toclaim 1, wherein: the first reflecting device includes a plurality ofhollow ridge prisms having total reflection.
 26. The arrangementaccording to claim 1, wherein: the first reflecting device includes apentaprism.
 27. The arrangement according to claim 1, wherein: the firstreflecting device includes a plurality of hollow ridge mirrors arrangedsuch that the plurality of polarized light bundles run perpendicular toa plane formed by at least one of the plurality of polarized lightbundles to be controlled and another one of the plurality of polarizedlight bundles that is controlled.
 28. The arrangement according to claim1, wherein: the first reflecting device includes a plurality of hollowridge prisms having total reflection, the plurality of hollow ridgeprisms being arranged such that the plurality of polarized light bundlesrun perpendicular to a plane formed by at least one of the plurality ofpolarized light bundles to be controlled and another one of theplurality of polarized light bundles that is controlled.
 29. Thearrangement according to claim 1, wherein: the first reflecting deviceincludes a plurality of pentaprisms arranged such that the plurality ofpolarized light bundles run perpendicular to a plane formed by at leastone of the plurality of polarized light bundles to be controlled andanother one of the plurality of polarized light bundles that iscontrolled.
 30. The arrangement according to claim 1, wherein: the atleast one second reflecting device includes a mirror.
 31. Thearrangement according to claim 30, wherein: the mirror corresponds to adielectrical mirror.
 32. The arrangement according to claim 1, wherein:the at least one second reflecting device includes a plurality ofmirrors arranged as a hollow cube corner corresponding to aretroreflector.
 33. The arrangement according to claim 1, wherein: theat least one second reflecting device includes a plurality of mirrorsarranged as a first hollow retroreflector and a second hollowretroreflector.
 34. The arrangement according to claim 1, wherein: theat least one second reflecting device includes a retroreflector formedof a massive prism.
 35. The arrangement according to claim 1, wherein:the at least one second reflecting device includes a plurality ofcube-corner prisms.
 36. The arrangement according to claim 1, wherein:the at least one second reflecting device includes a plurality ofmirrors forming an angle of 90°.
 37. The arrangement according to claim1, wherein: the at least one second reflecting device includes aplurality of pairs of mirrors, each pair forming an angle of 90°. 38.The arrangement according to claim 1, wherein: the at least one secondreflecting device includes a 90° prism.
 39. The arrangement according toclaim 1, wherein: the at least one second reflecting device includes aplurality of prisms.
 40. The arrangement according to claim 1, wherein:the at least one second reflecting device includes a plurality ofpentaprisms.
 41. The arrangement according to claim 1, wherein: the atleast one second reflecting device includes a plurality of ridge prisms.42. The arrangement according to claim 1, wherein: the at least onesecond reflecting device includes a plurality of mirrors that form afirst hollow ridge reflector and a second hollow ridge reflector. 43.The arrangement according to claim 1, wherein: the first reflectingdevice, one of the plurality of electrically controllable liquid crystalcells, and the at least one second reflecting device are arranged suchthat light that is controlled so as to be an inverse of light capable ofbeing extracted from one face of the beam splitter, emerges on anotherface of the beam splitter so as to be offset with respect to thenon-polarized light to be controlled.
 44. The arrangement according toclaim 1, wherein: each of the light bundles of the plurality ofpolarized light bundles passing through on the same face of the beamsplitter has a preselected distance from each other.
 45. The arrangementaccording to claim 1, wherein: a liquid crystal of the plurality ofelectrically controllable liquid crystal cells is present in a chiral,inclined phase.
 46. The arrangement according to claim 1, wherein: aliquid crystal of the plurality of electrically controllable liquidcrystal cells is present in a chiral, smectic phase.
 47. The arrangementaccording to claim 46, wherein: the liquid crystal is present in achiral, smectic A* phase.
 48. The arrangement according to claim 1,wherein: a liquid crystal of the plurality of electrically controllableliquid crystal cells is present in a helical, ferroelectric phase. 49.The arrangement according to claim 1, wherein: a liquid crystal of theplurality of electrically controllable liquid crystal cells is presentin a smectic, ferroelectric phase.
 50. A method for achieving anelectrical control of an intensity of a non-polarized light, comprisingthe steps of: acting on a polarizing beam splitter by the non-polarizedlight to be controlled via a first face of the polarizing beam splittersuch that the non-polarized light is split into a plurality of polarizedlight bundles that are orthogonal with respect to each other;configuring a first reflecting device for a reflection of at least oneof the plurality of polarized light bundles such that each of theplurality of polarized light bundles runs in parallel; arranging into apath of the plurality of polarized light bundles at least oneelectro-optical element that is penetrated by beams of the plurality ofpolarized light bundles and that changes a polarization of the pluralityof polarized light bundles as a function of a supplied control voltage;causing a second reflecting device to reverse a direction of theplurality of polarized light bundles after the plurality of polarizedlight bundles leave the at least one electro-optical element, intothemselves or offset in parallel, and causing the second reflectingdevice to send the plurality of polarized light bundles to the at leastone electro-optical element for a second time; and changing thepolarization of the plurality of polarized light bundles in the at leastone electro-optical element such that a sum of the changes of thepolarization of the plurality of polarized light bundles in a passagethrough the first reflecting element, a subsequent passage through theat least one electro-optical element, a subsequent reflection at thesecond reflecting element, a second passage through the at least oneelectro-optical element, and a second passage through the firstreflecting element generates an overall change in the reverse directionof the polarization of the plurality of polarized light bundles, whereinthe sum of the changes, as a function of the control voltage at the atleast one electro-optical element, conveys a light of the plurality ofpolarized light bundles in the polarized beam splitter to one of thefirst face of the polarizing beam splitter and to a second face of thepolarizing beam splitter.